The object of the invention is the development of a process and apparatus for non-contact measurement of the length of moving shaped bodies, and particularly of red-hot semifinished articles, by scanning the object with a high-speed television camera.
The production of metallic tubes, round stock and other profiles or shapes is accomplished by extrusion presses, among other things. When this is done, red-hot ingots are rerouted to the rolling machine on a roller device after the free fall from the extrusion press installation, for example. The exact knowledge of the total length of the ingot is critical for the further processing of it, because scrap waste and return motion--i.e., economic aspects--depend on it.
The exact measurement of the length of such starting materials or semifinished articles before entering the roller presents a problem since it must be accomplished on the red-hot moving bodies. A corresponding problem in measurement under the same difficult conditions also arises, for example, in rolling sheet metal on hot rolling trains. Up to the present, obtaining an exact measurement of the length (better than .+-.1 cm) of these parts failed because no methods were known by which non-contact measurements could be made on the moving object at a speed corresponding to the rhythm of production. Processes that are based on infrared radiation failed because of the so-called "halo" of the glowing parts.
Therefore, it was the task of the present invention to find a process and a device for accomplishing non-contact measurement of the length of moving shaped bodies, and particularly red-hot semifinished products, by means of which a reliable accuracy of measurement of better than .+-.1 cm is obtained.